I've been working on that for a while.
It's not easy.
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Step one would be to find out what percentage of surfers can tell the difference when the (single) fin is changed in their board, and they don't know what fin is in the board when they ride a wave, and they give a ride report after each wave without knowing which fin they were riding. The ride report should ideally be recorded by a 'blinded' person (= who does not know which fin was in the board).
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Then, load the board with TNT and blow it up.
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The double blinded stuff would of course be too tricky for the average viewer, ahh well....